Expansion Vessel

[stephens]

Could anyone tell me if replacing the expansion vessel (on a Worcester Bosch combi 28i RSF) is best left to the manufacturer or is it an easy job and a good heating engineer will be able to replace without problem? Many thanks for any advice.

 

[Puddle]

Its not hard to replace,any engineer should be able to carry out works, you will have to take the boiler off the wall though to gain access at rear
But why is it being replaced,if not leaking just re-prime,if leaking another option,if room, is to isolate expansion vessel inside boiler and fit external expansion vessel next to boiler

 

[danielp]

or just her worcester to do it its there warranty or a worcester accredited engineer

 

[stephens]

Thanks for that puddle and danielp. The boiler is 4-5 years old and is due for a power flush this Thursday as it has been through 6 auto air vents, the last only lasted 9 months! It was chemically cleansed (X400) at 2 years old but still they fail, so power flush and MagnClean are last resort. However when the air vent was replaced last Thursday, under guarantee, the engineer, nice chap, said the expansion vessel was flat and pumped it up for me. Since then the system pressure has dropped 0.2-0.3 bar and when the heating is on it rises a bit over the expected 0.25-0.5 bar increase, perhaps 0.6 from cold. With the power flush being soon, I just wanted to have decided whether to use Worcester themselves or the heating engineer doing the power flush, if it does deflate again soon. It probably won't be under guarantee now so I will keep my fingers crossed that it settles down OK and just get the power flush guy to check it out when he is doing the above work if, as you say, it is not a difficult job where familiarity would be an advantage. Having spent the last 4 years always expecting to find the next pool under the boiler I will just be glad to get it behaving as it should. Whatever happened to those old simple boilers we used to use?! Thanks again for your advice.

 

[kwakerdude911]

if its a gas boiler then a gas safe registered engineer (just to look at it) will be needed or you are breakin the law

 

[leakylea]

a faulty expansion would really send your pressure through the roof and your prv would blow basically every time your heating came on as there would be no room for any expansion
it might want slightly charging

 

[stephens]

Thanks for that leakylea, I might be OK now. As mentioned above the Engineer who replaced the Auto Air Vent said it was flat and pumped it up again. I then noticed a pressure loss and presumed it was deflating again as I could not see any leaks. Luckily I have just noticed dripping from the pipe outside so I am guessing he had opened the Pressure Relief Valve before installing the new Auto Air Vent and, as these things do sometimes, it has not seated properly and has started leaking. With a bit of luck the expansion vessel is OK and I only have to replace the PRV, which the heating engineer might be able to get before he power flushes on Thursday. Fingers crossed. Thanks again.